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See-through brains reveal memory pathways for pleasure and fear

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ONE region, two routes. Memories of pleasure and fear are laid down in the same part of the brain, but along different pathways.

Karl Deisseroth of Stanford University and his team gave mice a pleasurable experience using cocaine, or frightened them with electric shocks. After death, the team washed away the fatty materials in the mouse brains, making them transparent. Dyes that highlighted previously active cells allowed them to see which networks of neurons were involved in each experience.

This could have implications for treating mental health disorders, says Deisseroth. Some drugs, as well as transcranial magnetic stimulation, target the prefrontal cortex. “Now we know the signals for fear and pleasure can be transmitted by different axonal projections, new targeted treatments might be envisioned,” he says.

Joff Lee at the University of Birmingham, UK, agrees that the finding might lead to better treatments. If we do not target the right neurons, drugs intended to reduce fear may inadvertently also affect how we process pleasure, Lee says.

This article appeared in print under the headline “Fear and pleasure work their way separately into memory”